1. Field of the Invention
The present invention relates generally to magnetoresistive (MR) read heads for use in magnetic heads for hard disk drives, and more particularly to a read head in which the leads are sunken through the G1 insulative layer and into the S1 shield layer, and wherein the track width is defined by the electrical lead spacing.
2. Description of the Prior Art
As is well known to those skilled in the art, hard disk drives store data in the form of magnetic data bits in a plurality of circular tracks on magnetic disks within the disk drive. To increase the areal data storage density of the disk, it is generally necessary to write smaller magnetic bits, such that an increased number of circular tracks per inch (TPI) can be written on the disk surface, and an increased number of data bits per inch (BPI) can be written within each circular data track. To read such smaller data bits accurately, it is necessary to develop smaller read head structures, such that individual data bits can be accurately discriminated in the data reading process.
Generally, prior art read heads include a magnetoresistive (MR) sensor that is disposed between two magnetic shields, wherein two insulation layers (one on each side of the MR sensor) electrically insulate the MR sensor from the magnetic shields. The spacing between the two magnetic shields is a significant parameter in allowing the MR sensor to discriminate between successive magnetic data bits of a data track, and the width of the MR sensor is a significant parameter in allowing the MR sensor to read data bits only from a single data track (and not read from adjacent data tracks, termed side reading). One way to reduce the shield to shield spacing is to reduce the thickness of the insulation layers that separate the MR sensor from the magnetic shields. However, significant difficulties have arisen in prior art read head structures in that electrical lead members must be disposed between the shields to make electrical contact with the MR sensor to provide read head data output signals. The insulation gap layers must be thick enough to provide adequate electrical insulation between the electrical leads and the magnetic shields, and the thickness of the leads in prior art heads has made the fabrication of this electrical insulation more problematic. Additionally, the sensitivity of the sensor is significantly reduced at narrow track widths, due to magnetic stiffening caused by the hard bias material at the MR sensor element edges. A need therefore exists for a read head structure in which the insulation layers can be fabricated as thin as is practical to avoid electrical shorts, such that the sensor gap distance can be reduced, and in which the read track width of the read head can likewise be reduced. As will appear from the following description, the present invention utilizes a sunken electrical lead structure that accomplishes these objectives.